In traditional SERDES designs, switching partial driver one by one with a delay line, and adding capacitor at output points are the two traditional designs to slow down the slew rate of the transmitter driver. However, both of these two traditional designs only slow down the slew rate of the transmitter driver, and the those two traditional designs cannot speed up the slew rate of the transmitter driver.
In some case, it is needed to speed up the slew rate of the transmitter diver. Therefore, researchers are trying to improve those designs to selectively slow down and speed up the slew rate of the transmitter driver.